It is known that a pneumatic tire, due to structures thereof, exhibits a cavity resonance phenomenon caused by the length of a circular tube inside the tire. Further, a pneumatic tire, regardless of the type, generates noise having cavity resonance frequency in the range of 200 Hz to 270 Hz according to a circumference length thereof, and said noise is a main cause for unpleasant vehicle-interior noise.
As described above, since air resonance in the interior of the tire is a generation factor of the vehicle-interior noise, a method for absorbing noise in the interior of a tire is effective as an improvement method. Examples of conventionally proposed methods include, as disclosed in JP200482387A (PTL 1), a technique of adhering short fibers to a tire inner peripheral surface. This technique is characterized in that the adhesive used for a tire inner peripheral surface is dried to form an adhesive layer with high rigidity and, consequently, rigidity increases at those portions to which short fibers are adhered.
Additionally, some passenger car tires adopt a tread having a pattern asymmetrical about the tire equatorial plane, from the viewpoint of abrasion resistance and the like. Such a tire has the problem that the rigidity tends to decrease on the side of the tread pattern where the negative ratio (the proportion of groove portions (portions not contacting the ground) in the tread) is higher, and the rigidity tends to be unbalanced in the lateral direction of the tread portion, with the result that good steering stability may not be obtained. This also applies to the tires with short fibers adhered to the tire inner circumferential surfaces as stated above.